Short data networks represent an emerging area of opportunity for optical fibers. In a short data network, the interconnect distance between components is short and space constraints typically require bent or tightly confined configurations for interconnects. In consumer electronic applications, for example, the interconnects may be subject to extremely tight bends (e.g. ≦3 mm radius) for at least a short period of time during use of the device for its intended purpose. As electronic devices and data networks become increasingly miniaturized, market demand for interconnect technologies capable of function under increasingly demanding conditions will continue to grow.
Adaptation of optical fibers to short data networks has heretofore been limited due to fatigue associated with internal stresses that arise within optical fibers when installed in confined or bent configurations. To expand the use of optical fibers in short data networks, it is necessary to develop fibers that resist fatigue and maintain performance when utilized in highly-stressed configurations.
One strategy for increasing the fatigue resistance of optical fibers was proposed in U.S. Published Patent Appl. No. 2011/0300367. In this application, an inner coating layer was included in the design of a coated fiber to improve fatigue resistance. The inner coating functioned as a hybrid cladding and was placed between the glass cladding and the intermediate (primary) coating. The hybrid cladding had a thickness of ˜20 μm or less and was formed by curing a composition that included a photo-curable base composition and a photo-acid-generating compound. The photo-curable base composition typically included acrylate monomers and/or oligomers. The photo-acid-generating compound reacted in the presence of the radiation used to cure the base composition to release an acidic fragment that altered the chemistry of the process to produce a hybrid cladding that led to a significant improvement in the dynamic fatigue resistance of the fiber.
In addition to fatigue resistance, fibers suitable for short data networks need to be amenable to standard fiber assembly processes to interface the fibers to the couplers and connectors needed to form interconnects between components within devices or between devices in a network. The first step in the fiber assembly process is to thermally strip away the primary and secondary coatings. Temperatures reached during standard stripping processes can reach 150° C. to 200° C. In order to implement hybrid claddings as a strategy for improving fatigue resistance, the hybrid cladding must be compatible with standard thermal stripping processes. It must be possible to strip the primary coating from the hybrid cladding without damaging the hybrid cladding or leaving residue of the primary coating on the hybrid cladding. If the hybrid cladding is damaged in the stripping operation or residue from the primary coating remains on the hybrid cladding, it becomes difficult to (1) insert the stripped fiber into ferrules and (2) affix connectors to the stripped fiber. The hybrid cladding must also be stable at customary stripping temperatures. Current optical fibers used in short data networks have poor stripping characteristics. There remains a need to develop optical fibers with the fatigue resistance needed for short data networks that are compatible with conventional stripping processes.